Device for chemical mechanical polishing

ABSTRACT

The present invention provides a chemical mechanical polishing device for polishing a wafer. The chemical mechanical polishing device comprises a platen, an outer polishing pad, an inner polishing pad, a slurry providing system, and a rotating carrier. The inner polishing pad is located on the platen. The outer polishing pad is mounted on the outer polishing pad and peeled off when abraded from overuse. The slurry providing system provides a slurry to the surface of the outer polishing pad. The rotating carrier holds the wafer and contacts the surface of the wafer with the slurry and the polishing pad to carry out the chemical mechanical polishing process.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates in general to a chemical mechanical polishing device (CMP device). In particular, the present invention relates to a plurality of polishing pads stacked on the platen in advance. Abraded polishing pads are peeled off of the other stacked polishing pads. After the stack is re-settled, chemical mechanical polishing is resumed with the new polishing pad.

[0003] 2. Description of the Related Art

[0004] At present, chemical mechanical polishing (CMP) is the only way to realize a true global planarization in the manufacture of integrated circuits. A semiconductor substrate is bathed or rinsed in polishing slurry while an elastomeric pad is pressed against the substrate and rotated so that the slurry particles are pressed against the substrate under load. The lateral motion of the pad causes the slurry particles to move across the substrate surface, resulting in chemical and mechanical removal of the substrate surface.

[0005]FIG. 1 shows a sectional view of the conventional CMP device. A rotating carrier 110 comprising a transmission shaft 100 is used for holding and rotating a wafer 120. A platen 140 rotates by a spindle 130. The polishing pad 150 is fixed on the platen 140 by the adhesive tape 160. In addition, slurry 180 is provided on the surface of the pad 150 by a slurry providing system 170. The wafer 120 is bathed or rinsed in polishing slurry 180 while the polishing pad 150 is pressed against the wafer 120 and rotated so that the slurry particles 180 are pressed against the wafer 120 to carry out CMP.

[0006] However, the polishing pad 150 will inevitably be worn during CMP, and the uneven surface of the polishing pad 150 negatively impacts the result of CMP. Therefore, the polishing pad 150 has to be changed after a specific time to ensure the result of CMP. During the replacement of the polishing pad 150, however, the CMP system must be shut down and additional operating personnel are needed to change the polishing pad. Moreover, as the polishing pad 150 must be fixed accurately on the platen 140 by the adhesive tape 160, errors caused by imprecision can negatively influence the result of the process.

SUMMARY OF THE INVENTION

[0007] The object of the present invention is to provide a CMP device and method. Stacked polishing pads are set on the platen in advance, whereby the polishing pads are aligned with each other. The polishing pad in use is peeled off of the stack when abraded due to overuse. After the stack is re-settled, chemical mechanical polishing is resumed with the new polishing pad. The replacement operation is simple, involving only removal of the abraded polishing pad and the adhesive tape. Therefore, additional operating personnel are not needed to change the polishing pad, and the operation of adjusting the polishing pads is omitted to eliminate human error. Hence, the stability of the CMP system is improved and the burden of staff resources is reduced.

[0008] To achieve the above-mentioned object, the present invention provides a chemical mechanical polishing device for polishing a wafer. The chemical mechanical polishing device comprises a platen, an outer polishing pad, an inner polishing pad, a slurry providing system, and a rotating carrier. The inner polishing pad is located on the platen. The outer polishing pad is located on the inner polishing pad and is peeled off when abraded from overuse. The slurry providing system provides slurry to the surface of the outer polishing pad. The rotating carrier holds the wafer and contacts the surface of the wafer with the slurry and the polishing pad to carry out the chemical mechanical polishing process.

[0009] Moreover, the present invention provides a chemical mechanical polishing method for polishing a wafer, comprising the following steps. First, a plurality of stacked polishing pads is provided, whereby the outer polishing pad contacts the wafer. A slurry is provided to the surface of the outer polishing pad, and then, the wafer is polished by the relative motion between the wafer and the polishing pad. Finally, the outer polishing pad is peeled when abrading, then the wafer is polished by the polishing pad beneath the abraded polishing pad.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings, given by way of illustration only and thus not intended to be limitative of the present invention.

[0011]FIG. 1 shows a sectional view of the conventional CMP device.

[0012]FIG. 2 shows a sectional view of the CMP device according to the embodiment of the present invention.

[0013]FIG. 3 shows a lateral view of the polishing pad set on the platen according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014]FIG. 2 shows a sectional view of the CMP device according to the embodiment of the present invention.

[0015] A rotating carrier 210 comprising a transmission shaft 200 is used for holding and rotating a wafer 220. A platen 240 rotates by a spindle 230, the rotating direction is shown by the arrows in FIG. 2. The stacked polishing pads (2501-2503) are fixed by adhesive tapes (2601-2603) on their respective undersides. In FIG. 2, the polishing pad 2501 is fixed on the polishing pad 2502 by adhesive tape 2601, the polishing pad 2502 is fixed on the polishing pad 2503 by adhesive tape 2602, and the polishing pad 2503 is fixed on the platen 240 by adhesive tape 2603.

[0016]FIG. 3 shows a lateral view of the polishing pads (2501-2503) set on the platen 240 according to the embodiment of the present invention. In FIG. 3, the stacked polishing pads are fixed on the platen 240, and the gap 2504 is used for tearing the polishing pad away.

[0017] In addition, slurry 280 is provided on the surface of the pad 2501 by a slurry providing system 270. The wafer 220 is bathed or rinsed in polishing slurry 280 while the polishing pad 2501 is pressed against the wafer 220 and rotated so that the slurry particles 280 are pressed against the wafer 220 to carry out CMP.

[0018] In the present invention, when the polishing pad 2501 is too worn or is used for a predetermined time (life time) to carry out CMP, operators need only peel off the polishing pad 2501 with a cylinder. After performing a Pad Break-In process to the polishing pad 2502 to remove the adhesive tape 2601 from the polishing pad 2502 and break in the polishing pad 2502, the wafer 220 is polished with the polishing pad 2502 till CMP is finished. Here, the operation of changing the polishing pad is simplified because the polishing pads are stacked and aligned in advance, so the additional adjusting operation in the prior art is abbreviated.

[0019] Accordingly, the invention not only simplifies the pad changing procedure and decreases maintenance time, but also decreases the cost of the process and human resources. Furthermore, the operation of replacing polishing pad according to the present invention is very simple, requiring only removal of the abraded polishing pad and the adhesive tape. Therefore, additional operating personnel are not needed to change the polishing pad, and the operation of adjusting the polishing pads is omitted to eliminate human error. Hence, the stability of the CMP system is improved and the burden of staff resources is reduced.

[0020] The foregoing description of the preferred embodiments of this invention has been presented for purposes of illustration and description. Obvious modifications or variations are possible in light of the above teaching. The embodiments were chosen and described to provide the best illustration of the principles of this invention and its practical application to thereby enable those skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled. 

What is claimed is:
 1. A chemical mechanical polishing device for polishing a wafer, comprising: a platen; an inner polishing pad locating on the platen; an outer polishing pad removeably located on the outer polishing pad; a slurry providing system, which provides a slurry to the surface of the outer polishing pad; and a rotating carrier for holding the wafer and contacting the surface of the wafer with the slurry and the polishing pad to carry out the chemical mechanical polishing process.
 2. The chemical mechanical polishing device as claimed in claim 1, wherein the outer polishing pad and the inner polishing pad are stacked on the platen.
 3. The chemical mechanical polishing device as claimed in claim 2, wherein the bottoms of the outer polishing pad and the inner polishing pad have adhesive tape fixing the outer polishing pad and the inner polishing pad.
 4. A chemical mechanical polishing method for polishing a wafer, comprising the following steps: providing a plurality of stacked polishing pads, whereby the outer polishing pad contacts the wafer; providing a slurry to the surface of the outer polishing pad; polishing the wafer by the relative motion between the wafer and the polishing pad; and peeling the outer polishing pad when abraded from overuse, and polishing the wafer by inner polishing pad.
 5. The chemical mechanical polishing method as claimed in claim 4, wherein adhesive tapes are located between the polishing pads to fix the polishing pads.
 6. The chemical mechanical polishing method as claimed in claim 5, wherein the adhesive tapes are located on the respective undersides of the polishing pads. 